Monitoring For Ozone

Donovan Rafferty Ecology

Ron Cunningham Oregon DEQ

Anthony Reneau Tanabyte Engineering

A review for station operators

The Air Monitoring Station The Monitoring Equipment Performing Quality Control

Checks Certifying Ozone Standards

What we will cover

You will learn…..

by making mistakes !

Work Tasks - Ozone 2005Task

Assignment1-Mar 8-Mar 15-Mar 22-Mar 29-Mar 5-Apr 12-Apr 19-Apr 27-Apr 3-May

Primary bench standard to CARB RCPlanning meeting- staff assignments StaffReview of last season StaffContact with property owners AlanOrder supplies RCSite AC's /check w Paula for service AlanOzone monitors prepped RC/Lab ratZero air sources prepped RC/Lab ratConfirm Multorpor as site for summer O3 JS/BBTraining of Aaron and Chris KS/MH/StaffCO equipment down: STAFF Repair recorders RC/Lab rat Program DL's for O3 LH/MH/KS Move and configure XMLPusher PCs Staff/KS/LHUPS in place StaffClean manifold - check fan StaffReplace probes with new teflon Staff/RCColored exhaust lines Staff/RCShelter cleanup, general site cleanup StaffRenew Internet Access accounts JSVerify phone line operation StaffVerify temp control operation StaffDAS setup: KS Handling of incoming data KS/JK setup hourly report to AirNow KS/JKMidway meeting and evaluation STAFFCalibrate monitors in lab RC/Lab ratCalibrate transfer-std in lab (6x6) RC/Lab ratStaff training MH/StaffSite Accessories ready for each site StaffSetup at each site StaffInstall met at CJHS site LH/StaffSpare monitor & transfer-std RCChart handling prep- QA sheet prep BBStart up review meeting StaffCelebrate our successes StaffList any problems to avoid in future Staff

Ozone sites include: 3 letter LASAR # NetworkSpangler Rd., Canby SPR 10093 SouthLotspeich residence, Talent TAL 10109 MedfordCascade Jr. High, Turner CJH 10130 SouthSE Lafayette, Portland SEL 10139 NorthSauvie's Island, Portland SIS 14152 NorthSt. John's Church, Milwaukie MSJ 23306 Southplus a possible visibility site at Multorpor

Installing Monitoring Equipment Connecting sample tubing to the

sample gas inlet fitting. Connecting the primary power. Connecting the recorder. Connecting the phone line. Connecting the temperature probe. Installation of Teflon® filter. Connecting the data logger.

The Monitoring Station

The Probe

Probe is made of Teflon®. The residence time is critical. EPA requires a sample residence

time of less than 20 seconds. At 2.0 LPM the maximum probe

length should be less than 170 ft. For 10 seconds the maximum

probe length should be 84 ft.

When you arrive at the site…..

Survey the structure housing the equipment for weather leaks, safety, and security.

Perform routine maintenance. If you find a problem, you are

responsible for seeing it is corrected.

Record the actions that you took.

Monitoring Checklist The Analyzer Check to see if the power is on. Is the sample flow set to 2.0 LPM? Is the selector switch in the

“operate mode”? Can you hear the solenoid valve

cycling?

Environmental Controls for Monitoring Equipment Instrument vibration (Never “stack

instruments”) Keep sunlight from “shining” on

instruments. Electrical voltage Temperature Security Cleanliness

Standard Operating Procedures Data collected using fully

documented procedures have much higher credibility.

Developed using the CFR’s and technical assistance documents.

If you didn’t record it ……

you didn’t do it.

Monitoring Checklist

Developed to help the first time operator or one that does it infrequently.

Quality Control Checks

Should be performed at least once every two weeks.

Inspection of the shelter and instruments.

Zero, Precision and Span Checks Adjustments

Never perform a calibration check on days forecasted to be above 90° F. unless there appears to be a problem with the ozone analyzer.

The current ozone standard is 80 ppb/eight hour average. Calibrations should never be performed when ozone values are elevated.

The Monitoring Equipment Ozone analyzers must meet

reference method or equivalent method specified by the EPA in Appendix D of 40 CFR Part 50.

Dasibi 1008PC

Dasibi Ozone Analyzers

Meet EPA designated equivalent method requirements when operated under the following conditions: Concentration range of 0 - .5 ppm Line voltage of 105 -125 vac Temperature of 68°- 86° F

The analyzers must be operated and maintained according to the Operating and Maintenance Manual to conform to the EPA Designation requirements.

Think of the instrument as being divided into two components…….

The Analyzer (Photometer).

Flow set to 2.0 LPM.

The Ozone Analyzer Technique

Based on the principle that ozone molecules absorb UV light (254 nanometers wavelength).

A column of air is illuminated at one end by an ultraviolet lamp.

The intensity of the lamp is measured at the opposite end by a detector.

The measurement is performed within the sample tubes (absorption tubes) of the analyzer.

Critical Components of an Ozone Analyzer (Photometer) Solenoid valve Ozone to oxygen converter Absorption tubes Sample pump UV lamp source Detector

Gas Valve: actuated by a solenoid

Ozone Scrubber

Scrubber Cartridge

copper screens coated with manganese dioxide

The MnO2 catalyzes the reaction of ozone to diatomic oxygen.

The sample entering the absorption cell after passing through the filter is preserved intact except for the ozone.

The Sample Pump

UV Lamp with output concentrated at 253.7 nm where absorption of ozone is maximized

Detector: Measures the intensity of the lamp

The Measurement

Each measurement cycle is completed within 10 to 20 seconds.

Each measurement contains two half cycles.

The First Measurement Half-Cycle Ambient air is directed by the

analyzer’s solenoid valve to the scrubber where any ozone present is converted to oxygen.

The ozone-free sample is directed through the absorption tubes.

The UV source lamp illuminates the sample and the transmitted intensity is measured by the detector.

The analyzer stores the intensity value.

Zero (reference) gas with the ozone “scrubbed”

Sample

The First Measurement Half Cycle

Solenoid

Scrubber

Absorption Tubes

Absorption Tubes The optical path length through the sample. Transmittance of the sample at a wavelength of 253.7

nm

The temperature and pressure of the sample

The Second Measurement Half-Cycle

The sample is directed to the absorption tubes.

The UV source lamp illuminates the sample.

The detector measures the transmitted intensity.

The Second Measurement Half-Cycle Any ozone present in the sample

absorbs some UV light resulting in a lower intensity value as measured by the detector.

This value is is subtracted from the previously stored value and the resulting difference is the amount of ozone in the ambient sample.

Sample without the ozone “scrubbed”

Sample

The Second Measurement Half CycleSolenoid

Absorption Tubes

At the end of The Measurement Cycle The measured result is displayed

on the instrument as a concentration.

Presented as an electrical signal to the data logger and the strip chart recorder.

Since ozone is a highly reactive gas, accurate concentration of the gas cannot be made and stored for any length of time.

To calibrate the analyzer, various concentrations of ozone must be made and measured on site.

Specific protocols have been developed to generate and measure accurate concentrations of ozone on site.

The Ozone Transfer Standard Think of as two instruments. One half makes ozone. The other half measures the

sample. Capable of generating and

measuring accurate ozone concentrations.

Critical Components of an Ozone Transfer Standard

Zero air source. Pump Flow controller Ozone generator Manifold

Ozone transfer standard

Ozone analyzer

Charcoal Column

Used to absorb ozone in ambient air while performing a zero check

Generator Pump

Flow Controller for ozone generator (5 LPM)

Ozone Generator:produces ozone for calibration check

Ozone Generator with Ultraviolet (UV) Lamp

The Ozone Generator

Incoming air is subjected to ultraviolet radiation from a mercury vapor lamp.

The oxygen absorbs the UV light. To dissipate the resulting gain in

energy, the irradiated O2 molecules split into two negatively charged oxygen atoms.

These atoms combine with unsplit oxygen to form O3.

The Manifold

A specific volume of ozone or zero air enters the manifold.

The calibrator pulls a “sample” from the manifold.

The instrument that is being check also pulls a “sample” from the manifold.

The excess is allowed to vent.

5 LPM

2 LPM for transfer standard

The Manifold

2 LPM + excess to analyzer

Capped

Ozone Scrubber

Pump

Flow Controller

Ozone Generator

Manifold

To transfer standard

capped

Analyzer

The Ozone Generator

Primary Standards and Transfer Standards Are used to verify the accuracy of

the instrument. Primary Standards have the

highest authority.

Primary Standards

Located at a central laboratory where it can remain stationary, protected from the physical shocks of transportation, operated by an experienced analyst under optimum conditions.

Serves as a common standard for all analyzers in a network.

Compared against other primary standards.

Compared against the Standard Reference Photometer (SRP)

Primary standards have the highest authority.

Participants of the SRP Program(SRP #4)

Arizona DEQ Ecotech LTD (Australia) California, Arizona,Hawaii, Utah EMPAC (China) Alaska,Oregon,Wash,Idaho Lawrence Livermore Labs National Park Service Vandenberg AFB Westinghouse Hanford Company

Ozone Transfer Standards

Transportable instrument Contains an ozone analyzer and

generator. Together with the associated

operational procedures, can accurately reproduce ozone concentration standards that are related to an authoritative primary or master standard.

P rim ary S tan d a rdE co lo gy

S ta nd ard R e fe re nc e P h o to m e te rC a lifo rn ia A ir R e s o u rc es B o a rd

P rim a ry P h o to m e te rR e se a rch T ria ng le P a rk

Primary Standards

Transfer Standards

1.035 11/2/19991.036 1/30/20001.036 3/20/20001.042 6/20/20001.04 9/4/20001.04 11/2/2000

1.039 1/20/20011.012 4/20/20011.017 4/26/20011.014 7/17/20011.015 4/15/20020.993 4/24/20021.009 7/15/20021.003 4/7/20031.005 8/2/20030.989 4/27/20040.995 4/28/20040.997 8/30/20040.987 12/6/2004

Ozone Transfer Standard #6452

True ozone = display x 1.00 - zero12/06/2004

0.97

0.98

0.99

1

1.01

1 2 3 4 5 6

Run Number

Slo

pe

Data Loggers and Telemetry Before performing any calibration

checks, disable the ozone channel. Joan Kiely (360) 407-6839

Performing the Zero Check Make sure the Transfer Standard

has warmed up. Set the ozone adjust thumbwheels

to 000. Set the ozone switch to the off

position. Turn the generator pump on.

Zero Check Record the values using the form

provided. Check the data logger and recorder to

make sure they are reading zero. Allow @15 minutes to sample zero air. Record the values using the ten count. Remember to subtract the zero offset

from all readings to obtain the true ozone reading.

The Precision Check

Turn the ozone lamp switch on. Set the lamp to AUTO. Set the thumbwheels to 090. Allow 15 minutes after the trace

plateaus. Record the values using the ten

count.

The Span Check

Set the thumb wheels to 400. Allow for the trace to plateau. Record the values using the ten

count. Multiply Match output of analyzer to data

logger and chart recorder

Determining the Precision of the Instrument

The precision of the instrument is the difference between the “actual” or true ozone value (measured by the Ozone Transfer Standard) and the “indicated value” (measured by the analyzer).

Indicated - Actual

ActualX 100 = Percent Difference

Percent Difference

Analyzer - Standard

StandardX 100 = Percent Difference

Percent Difference

After the Calibration Check Record the sample chamber

temperature. Record the unadjusted sample

frequency. Record the sample chamber

pressure. Record the control frequency

50.000.

Performance Checks

Sample Flow Check Span Check Control Frequency Check Sample Frequency Check

Sample Flow Check

Tap the flowmeter to make sure the float is not stuck.

Should read @ 2.0 L/min.

Adjust if less than 1.8 L/min or greater than 2.2 L/min.

Never lower than 1.5 or higher than 3.5 L/min

Span Check

Turn mode switch to SPAN. Should read 30.8xx Set in lab. Do not adjust. If it does not read 30.8xx, contact

David at the lab.

Control Frequency Check Should always be 50.000 on the

display If not, contact David.

Sample Frequency Check Should not be below 410 KHz. Track the degradation. Large drops indicate dirty optics. Adjust frequency between 460 KHz

and 410 KHz.

To adjust the sample frequency Set mode selector switch to

SAMP/TEMP with T/P off. Loosen the dual screws on the

Light Source Block. Push lamp in to increase, pull out

to decrease the lamp intensity, or rotated. Small movements needed.

Tighten screws when done.

Pressure Check

Check the analyzer pressure against a certified barometer.

0.5-micronTeflon® Filter

Intalled before entering the analyzer.

Will not degrade the ozone concentration.

Change filters regularly.

The .5 micron teflon® filter holder

Remember to change filter when dirty

Diagnostic LED

Diagnostic LED 0 = No faults 1 = Not used yet 2 = Sample Frequency is not above 300

Khz, or is not below 480 Khz. 3 = Control Frequency is not at 500 Khz. 4 = Lamp heater voltage is incorrect. 7 = CPU reset occurrence. 8 = Displayed whenever any front panel

switch not in the correct position for proper operation.

Patience is a Virtue

Allow yourself enough time. How fast you can do it means

nothing. If you rush you are bound to make

mistakes. Mistakes usually cost lost data,

time and money. The best operators take their time,

are methodical and thorough.

Before Leaving the Station……. Record the results of the

calibration check and any changes that were made to the instruments.

Make sure that the analyzer is running and that all the switches are in their correct positions.

Enable the data logger. Make sure that the station is

secured.

Before you leave……..

Check to see if the power is on. Is the sample flow set to 2.0 LPM? Is the selector switch in the

“operate mode”? Can you hear the solenoid valve

cycling? Has channel 03 on the data logger

been disabled?

Strip Charts

Before performing any calibration checks, annotate the strip chart.

Make your entry into the logbook. Sean Lundblad (360) 407-6843

Quarterly Quality Assurance Audits

A Quality Assurance representative visits the site quarterly.

Challenges the station analyzer with concentrations generated by the QA transfer standard.

Checks for the accuracy of the analyzer. Discusses issues that arise during the

audit.

The Critical Criteria TableOZONE CRITICAL CRITERIA TABLE

Criteria Acceptable Range Frequency40 CFR

Reference

Standard Reporting Units ppm All data 40 CFR, Pt 50.9

Completeness (seasonal)

Maximum 1-hour concentration 75% values from 9:01 AM to 9:00 PM (LST) Daily 40 CFR, Pt 50, App H, S 3

Precision

Single analyzer

Reporting organization

None

(See note A below)

1/3 months

1/2 weeks for seasonal sites orsites where manual QC checks areperformed.

1/4 weeks at year roundautomated sites.

(See note B below)

95% CI < +/-15%

40 CFR, Pt 58, App A

EPA-600/4-83-023Vol II, App 15, S 6

Accuracy

Single analyzer

Annual accuracy

None

(See note C below)

95% CI < +/-20%

25 % of sites

quarterly (all sites yearly)

40 CFR, Pt 58, App A

EPA-600/4-83-023Vol II, App 15, S 6

Quality Control Check

Zero/span check -level 1If Cal updated at each zero/span

Zero/span check -level 1 If fixed Cal used to calculate data

Zero Drift < +/- 20 to 30 ppbSpan Drift < +/- 20 to 25%

Zero Drift < +/- 10 to 15 ppbSpan Drift < +/- 15%

1/ 2 weeks Vol II, S 12.6

Vol II, S 12.6

The Operational Criteria TableOZONE OPERATIONAL CRITERIA TABLE

Criteria Acceptable Range Frequency40 CFR

Reference

Shelter Temperature

Temperature range

Temperature control

20C - 30C

or

Instrument must be operated per manufacturerspecifications

(See Note D below)

2 C

Daily

Daily

40 CFR, Pt. 53.20Vol II, S 7.1 1/

Change 40 CFR to state the following:Instrument must be operated per manufacturer

specifications

Ozone Analyzer Calibration

Multipoint calibration

(at least 5 points) Linearity error < 5%

Upon receipt,adjustment, or 1/year ifcontinuous QC checks

or

1/6 months if manualQC checks

Zero Air Free of any substance that might rect withozone

Performance Evaluation

(NPAP)

State audits

Mean absolute difference < 15%

State requirements

(See note E below)

1/year at selected sites

1/year

Vol II, S 16.3

Vol II, App 15, S 3

Update 40 CFR to include audit control limitsonly. Update Volume II to include revised auditranges (i.e. 50ppm, 100ppm, and 200ppm)

The Systematic TableOZONE SYSTEMATIC CRITERIA TABLE

Criteria Acceptable Range Frequency

40 CFR

Reference

Detection

Noise

Lower detectable level

.003 ppm

.003 ppm

40 CFR, Pt. 53.20 & 23

“

Transfer Standard

Qualification and certification

Recertification to local or State primarystandard

+/- 4% or +/-4ppb (whichever greater)RSD of six slopes < 3.7%

Std. Dev. of 6 intercepts < 1.5%New slope = + 0.05% of previous

Upon receipt of transferstandard

Beginning and end ofozone season or 1/6

months whichever less

EPA-600/4-79-056

EPA-600/4-79-057

Local Primary Standard

Certification/recertification to StandardPhotometer

(if recertified via a transfer standard)

Difference < +/-5 %(preferably +/- 3%)

Regression slopes = 1.00 +/- 0.03 and twointercepts are 0 +/- 3 ppb

1/year

1/year

Determination of O3 by Ultraviolet Analysis (draft)

“

EPA Standard Reference PhotometerRecertification

Regression slope = 1.00 + 0.01 and intercept < 3 ppb

1/year Protocol for Recertification of Standard Reference Photometers

(See note F below)

Siting CriteriaAppropriate to Scale 40 CFR Part 58

Equipment

O3 AnalyzerReference or Equivalent Method

Purchase Specification 40 CFR Part 53.9

EPA 600/4-079-057

Data Validation Tables

Critical precision and accuracy

Operational shelter temperature

Systematic certified ozone standard or SRP comparison

Bad data…

is worse than no data at all.

Maintaining Your Monitoring Equipment

Break to the Technical Assistance Lab.

Calibration Lab (360) 407-6030